I used to have a cat I could let out on the back patio with me, and she would stay on whatever concrete pad we had out there. I moved a few times, and each time we would do this routine when we went outside the first time where she would put one paw like this and look at me and wait. Without much change in my tone I could just say ‘yea’ or ‘nope’ and she’d learn where she’s allowed to go. It was always pretty obvious, just a concrete pad, but shed test the boundaries anyway. There was never any friction, shed just accept it and test the next spot. But one time I tried seeing how specific she would go, and I said ‘yea’ to some railroad ties lining a flower bed on one side of the patio. For the rest of my lease, she would not step foot in the flower bed but would do a loop on the railroad ties and come back to the concrete. I’m not sure where I’m going with this, maybe your desk needs railroad ties